Field of the Invention
The invention relates in general to an electric field sensor array device and a method of manufacturing the same, and more particularly to a composite substrate sensor device and a method of manufacturing the same.
Description of the Related Art
A conventional non-optical type sensor array device, such as an electric field/capacitive, a thermal or a pressure sensing device applied to a fingerprint sensor, needs to sense the textures of the finger, and thus needs to have the essentially enough sensing area contacting the finger to obtain the sufficient sensing accuracy. For example, an electric field/capacitive fingerprint sensor has sensing members arranged in an array, wherein an area covered by these sensing members is the same as the sampled area of the finger. For example, in a fingerprint sensor with the resolution of 500 DPI, a pitch of the sensing members of the sensing device is equal to about 50 microns (um), and each sensing member comprises a sensing electrode cell and a corresponding sensing circuit cell thereinbelow, which are usually integrated in a semiconductor integrated circuit (IC) device, which is fabricated by a complementary metal oxide semiconductor (CMOS) manufacturing process, for example. The sensing electrode cells are formed on a top metal layer of the manufacturing process to define the pitch of the sensing members, while the corresponding sensing circuit cell is formed below or under the sensing electrode cell to form a monolithic configuration. However, when such a monolithic configuration is applied to an area sensor, the dimension of the sensing electrode cell array and its corresponding sensing circuit cell array must be equal to the dimension of the sensing area. That is, the conventional electrode cell and circuit cell have the same pitch dimension, so that the sensing area is equal to the area of the sensing members. For example, if the sensing array has 100×100 sensing members, then the 5 mm×5 mm sensing electrode cell area and the 5 mm×5 mm sensing circuit cell area thereunder need to be provided. If the peripheral analog and digital circuits are added, then the overall area of the fingerprint sensor or chip is very large, so that the device cost is relatively high.
Therefore, how to reduce the area of the sensing members while keeping the equivalent large sensing area is an innovation to be proposed.